1. Field of Invention
The present invention relates to the field of lighter-than-air vehicles.
2. Description of Related Art
Lighter-than-air vehicles, particularly the non-rigid type, have been used for a variety of applications including rescue, cargo transportation, and meteorological research. In a typical case, an airship is launched with the hull fully and stiffly inflated, ascends to a target altitude, performs its mission, and returns to the ground with the hull still fully inflated. One or more ballonets are used to keep the hull under pressure in order to maintain the rigid shape of the hull during the ascent and descent through the atmosphere. The ballonets are typically fully inflated at take-off and gradually depressurized or vented to ascend the airship, then inflated again to descend the airship. However, ballonets and their associated pump equipment increase the size, weight, and cost of the airship. Accordingly, new technology is needed.
The invention provides high-altitude atmospheric airships (and methods for operating same) that are capable of traversing the lower atmosphere without a heavy weight hull, ballonets, or a high-powered propulsion system. The airships may include a non-rigid hull and an airship rotating device.
The hull of an airship may be partially inflated with a lifting gas at ground level to float the airship. When a predetermined altitude is reached, the airship may be rotated into a flight attitude (e.g. level) by the airship rotating device.
The airship rotating device may be a self-righting ballast, for example. The self-righting ballast may include a rear fluid reservoir connected to a forward fluid reservoir by a fluid conduit mounted on the airship hull. The fluid may be moved between the rear and the forward reservoirs to rotate the airship into the flight attitude. For example, the fluid may be moved to align a center of gravity of the airship with a center of buoyancy of the airship. Other types of self-righting ballasts may also be used, such as moving a weight between two points anchored on the hull.
To return to ground level, the airship may include a lifting gas release device such as a selectively ignitable pyrotechnic fuse attached to the hull. When ignited, the pyrotechnic fuse releases the lifting gas from the airship hull, thus permitting the airship to descend. An aerodynamic decelerator such as a parachute may be used for aerodynamically decelerating the airship to ground level.
Other sensors and detectors may be included in the airship such as altitude, yaw, roll and pitch sensors. The altitude sensor may be used to detect when a desired altitude has been reached, and the yaw, roll and pitch detectors may be used to determine airship attitude and orientation. A low-powered propulsion system may also be provided for propulsion, if needed.